Another Kenwood KA-5700 Recap & BOM

Discussion in 'Kenwood-Trio/Kensonic-Accuphase' started by Spenser, Aug 24, 2017.

  1. gpounce32768

    gpounce32768 AK Subscriber Subscriber

    Messages:
    361
    Location:
    Baltimore, MD USA
    12v on an led assembly designed for 8v ac or dc will dramatically overpower it- led will burn out for sure. If you have a spare, you could put another resistor in series- to reduce the current- which would let the 8v led assembly operate normally. I like the bright spectrum though I also like the cooler incandescent if its a clear bezel- the 5700's is a great candidate for that, I did an onkyo a while back with an incandescent indicator liked that too.
     
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  2. 8xlaxx

    8xlaxx Super Member

    I was able to get to Advance Auto Parts yesterday and dropped in the clear, 14V incandescents. They are dimmer but at least I am not having a voltage issue anymore and hope they last longer in the tuner and amp. @gpounce32768 was correct, I think the 8v LEDs were getting overpowered in the circuit as I was seeing 12v at the first buld in series.
     
  3. 8xlaxx

    8xlaxx Super Member

    @Spenser @hopjohn @gort69

    I did a total re-cap of my KA-5700 last night using the BOM that @Spenser posted.

    I am having issues with the amp. The amp was working perfectly prior to the re-cap. On power up the older relay pinged at approx. 2 seconds. Now, the amplifier is dead, no ping with the new diodes, relay & transistor. I would like to ask, where should I start looking for the problem? There are no blown fuses. Is it possible that I might have reversed the polarity of the transistor, diode or cap? I will re-check my work but wanted to put a post up on AK for some help.

    Thank you.
     
    Last edited: Sep 24, 2017
  4. hopjohn

    hopjohn Kenwood Krazy Subscriber

    Messages:
    846
    Location:
    Dallas, TX
    So you did a recap and made diode and transistor changes? Check everything. Cap polarity, diode polarity. Check transistor datasheets new and old to see if there were differences in pinout. If you're relatively new to this I'd suggest only going in small stages before testing. That way if something goes astray you're not at a loss as to where to look. Fortunately, the 5700 doesn't have too many things to change.
     
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  5. 8xlaxx

    8xlaxx Super Member

    Thank you @hopjohn

    I just double checked the polarity and parts numbers of all the caps. All were OK.
     
    Last edited: Sep 24, 2017
  6. 8xlaxx

    8xlaxx Super Member

    @hopjohn

    Your advice was spot on. Right away, I decided to go for the transistor relay Q26 2SC1213 512-KSC2690AYS BJT NPN. I pulled and reversed it on the board then tacked it back in,... got relay 'ping'. Amp is up and running now, will let it break in a little bit at low gain.

    Again thank you!

    EDIT: Below is the mistake I made. C2690A-Y was reversed.

    FC1A0868.JPG
     
    Last edited: Sep 24, 2017
  7. gort69

    gort69 AK Subscriber Subscriber

    Messages:
    810
    Location:
    Vancouver, WA
    The marking on the board will look similar to this >I or this I<, (for zeners, more like this Z>, <Z) and the diode will have a band around one end. The band on the diode goes to same end as the vertical line (or Z) on the board. (You really should make a note that the board marking is correct before removing the original diode since board mismarkings are not unheard of. I don't recall that being the case on the KA-5700 though).
     
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  8. 8xlaxx

    8xlaxx Super Member

    Thank you @gort69

    I went with below and had installed them correctly first go.

    [​IMG]
     
  9. 8xlaxx

    8xlaxx Super Member

    @Spenser

    My apologies for the repeat thread hijack. Thank you, very helpful and a timely one!

    Did you start the KT-5500 project yet?

    FC1A0869.JPG
     
  10. gpounce32768

    gpounce32768 AK Subscriber Subscriber

    Messages:
    361
    Location:
    Baltimore, MD USA
    Congratulations on getting it running :) I like my 5700 a lot, sounds great, it was fun to fix up and the tone control circuit built into the feedback is very interesting.
     
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  11. Spenser

    Spenser AK Subscriber Subscriber

    Messages:
    140
    Location:
    Pittsburgh, PA, USA
    Good job!

    My apologies. Was off doing some other things.

    I just sent a very draft parts list and BOM to you through the other thread for the KT-5500.
     

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